The project is concerned with speech perception. It proposes a series of 16 interrelated experiments, some of which are new and some of which are expanded and enfolded from Research Grant R29-NS titled "Auditory-Visual Perception of Speech by Adult." This research asks fundamental questions about the nature of speech perception cues, the answers to which will increase our understanding of spoken language and be of value in the management of neuromotor speech disorders. Previous studies have demonstrated that the perception of speech is not solely an auditory process. Visual information from a talker's mouth and face can also play an important role in spoken language processing, for both the hearing-impaired and normal-hearing adults. Research from this laboratory has shown that visual information can influence phonetic processing in a manner similar to the corresponding auditory information. The proposed research will examine the processes involved in the integration of auditory and visual information during phonetic perception. Three issues will be addressed: (1) whether the visual information is equivalent to, and processed independently of the auditory information during speech perception, (2) whether only particular aspects or "cues" in the auditory and visual signals are relevant for phonetic processing, and (3) whether the original auditory information is available for further processing after it has been integrated with the visual information. The results from these experiments should have important implications for models of speech perception and development. In addition, they should be relevant to clinical concerns for aural rehabilitation of the hearing- impaired and for the management of those with neuromotor speech disorders.